Sorry I cant help you out there, I Bf mine til 14 mths, I think my Gf with twins used to make it up in a jug, using a bamix to mix it at night ( they were on diff formula's as one had reflux ) so she had a big jug with their name on it in the fridge, and would just pour it intl the bottle as needed.

good on you for joining amba, in those early days its a lifesaver ( well a brain saver anyway ) someone at amba might have another idea on the bottle situation.